According to the development of modern technology in science and the accompanied increased interest in the quality of life, the importance of diagnosis/prevention of disease, food, and other environments surrounding human is growing as well. As a result, the necessity to measure the concentration of an organic material or an inorganic material in a sample is growing in order to diagnose disease or to analyze a pollutant in environment or for a specific process in the field of food chemistry and in industrial chemistry as well. Most of all, our best interest is in the biosensor which enables serial and swift analysis of multiple components and thus is regarded as one of the promising alternatives for the conventional methods in relation to clinical tests, measurement of food freshness and contamination, bioprocess control, and environment monitoring.
Biosensor is a device to measure the concentration of a target material by the following procedure: binding a biomaterial such as an enzyme, a microorganism, an antibody, a receptor and a DNA probe to an electronic or physicochemical transducer; detecting any electrochemical, optical, thermal, or piezoelectric signal generated from the reaction between the target biomaterial and the transducer; and measuring the concentration using the signals. In particular, the immunosensor using the property of forming an antigen-antibody complex is characterized by high selectivity and low detection limit because of specific recognition of antigen-antibody. Every material that can generate an antibody can be a target of such immunosensor, because of which it is highly spotlighted as a medical diagnostic sensor.
The measurement with the immunosensor is accomplished by using solid phage sandwich enzyme-linked immunosorbent assay. Solid phage sandwich enzyme-linked immunosorbent assay demonstrates excellent sensitivity, compared with any other immunoassay, owing to the specific reaction induced when an antigen binds to the fixed antibody and then label (enzyme, fluorescein, colloidal gold, latex bead) conjugated secondary antibody is bound to another immunobinding site on the antigen.
That is, in the method of solid phase competitive enzyme-linked immunosorbent assay, intervention by steric hindrance made by another material might be observed in the substrate under reaction, resulting in blocking of the signals. On the other hand, in the method of sandwich enzyme-linked immunosorbent assay, immune response is a specific reaction induced only in the immunobinding site, indicating that intervention by another material is less in the substrate, so that the signals are hardly blocked. Pathogenic bacteria, viruses and cells, the high-molecular proteins, to be analyzed in a given sample and in a standard material are conjugated with a fixed antibody, which were washed. Thereafter, a label conjugated secondary antibody is bound thereto.
Therefore, the amount of the remaining enzyme on the solid phase is in proportion to the amount of the analyte. The unbound secondary antibody label conjugates are washed away. The amount of the secondary antibody-label conjugate bound on the solid phase by immunobinding can be measured with various measurement methods according to the characteristics of different markers. Sandwich enzyme-linked immunosorbent assay demonstrating excellent specificity and sensitivity is advantageous in quantification of protein analytes. Thus, this method is generally used for the analysis of clinically important blood proteins. This method also facilitates the analysis of low-molecular analytes via competitive enzyme-linked immunosorbent assay. That is, the cartridge for sensor of the present invention is applicable to sandwich (non-competitive) enzyme-linked immunosorbent assay and competitive enzyme-linked immunosorbent assay as well.
Lab-on-a-chip is named so because it is designed to perform all the bio-experiment processes including reaction, washing, and detection in the chip with only one injection of a sample. Particularly, every necessary devices are accumulated on a few cm2 sized glass, silicon, or plastic chip by using micro machining technique. That is, it is a microprocessor on which various techniques of immunology, electronic control, microfabrication, and hydrodynamics are integrated to facilitate high-speed, high-efficiency, low-cost, automatic analysis.
This technique becomes an important skill to reduce cost and time necessary for the screening of a new drug in the fast growing pharmaceutical industry. In addition, this technique is a key method that can be applied to various fields including medical diagnostic apparatus, health examination device for home or hospital, chemical or bioprocess monitoring, portable environmental pollutant analytical instrument, unmanned chemical/biological agent detection/identification apparatus for CBR, etc.
Lab-on-a chip technique is based on the capillary electrophoresis developed by Harrison et al in early 1990. They applied voltage on the both ends of a microchannel filled with a solution to cause capillary electro-osmosis forming solution flow. So, the solution flow was controlled without any additional pump or valve and separation analysis was made possible by using the capillary electrophoresis, suggesting that it was possible to build a small lab on a chip. However, even though the materials were good enough to form a microcapillary tube, it was still difficult for mass-production. Most applications of lap-on-a chip are one-time biochemical sensors, indicating that there are problems of reproducibility and production cost. To flow fluid between chambers, micro valves have to be used and washing process is required, which make the device complicated.
The present inventors tried to develop a biosensor which not only enables quantitative/qualitative measurement of one or more components in a sample by one time sample injection but also facilitates mass-production with low cost owing to the simple structure and easiness in preparation and carry. As a result, the inventors found out that one or more components could be detected by one time sample injection by using the cartridge equipped with a microfluidic channel formed between a substrate and an adhesive layer in which sample inlet-sample chamber-detecting part-disposal chamber are all connected in that order, leading to the completion of the invention.